The present invention relates to an electronic musical instrument of the type in which when a player depresses a key of the keyboard so as to produce a tone, a tone above or below the selected tone by, for example, a perfect fifth is also automatically produced and mixed with the selected tone, whereby the player can play from solemn musics to gimmick musics.
When a player plays an electronic musical instrument , he or she simultaneously depresses two keys spaced apart by one octave so that various sounds can be produced. However, it is very difficult for a player to play a music at a fast speed with a single hand and it is next to impossible to simultaneously depress the keys spaced apart by two octaves by a single hand. As a result, the player must accept poor and unsatisfactory musical tones even though more solemn and wide tones are desired.
In the conventional electronic musical instrument, a data processing means or unit receives or transmits input or output data over long transmission lines because of the shape of the musical instrument. In addition, the electronic musical instrument must process a very large amount of data within a very short time interval in order to produce various sounds. In order to shorten the data processing time, the clock frequency of the data processing unit must be increased as high as possible. However, the increase in clock frequency frequently results in erratic operations. When the clock frequency is lowered in order to avoid erratic operations, the data processing time is increased so that the electronic musical instrument cannot perform its functions satisfactorily.